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Biomedical subjects

D D Jones

Publications and source records attributed to D D Jones.

At least 19 recordsLinked to original sources
PubMed1992

Local regeneration in the retina of the goldfish.

We have studied regeneration of the retina in the goldfish as a model of regenerative neurogenesis in the central nervous system. Using a transscleral surgical approach, we excised small patches of retina that were replaced over several weeks by regeneration. Lesioned retinas from three groups of animals were studied to characterize, respectively, the qualitative changes of the retina and surrounding tissues during regeneration, the concomitant cellular proliferation, and the quantitative relationship between regenerated and intact retina. The qualitative and quantitative analyses were done on retinas prepared using standard methods for light microscopy. The planimetric density of regenerated and intact retinal neurons was computed in a group of animals in which the normal planimetric density ranged from high to low. Cell proliferation was investigated by making intraocular injections of 5-bromo-2'-deoxyuridine (BUdr) at various survival times to label proliferating cells and processing retinal sections for BUdr immunocytochemistry. The qualitative analysis showed that the surgery created a gap in the existing retina that was replaced with new retina over the subsequent weeks. The BUdr-labeling experiments demonstrated that the excised retina was replaced by regeneration of new neurons. Neuroepithial-like cells clustered on the wound margin and migrated centripetally, appositionally adding new retina to the old. The quantitative analysis showed that the planimetric density of the regenerated neurons approximated that of the intact ones.

Animals↗
PubMed1992

Norepinephrine inhibits rat pre-adipocyte proliferation.

Hormonal and neural status are major determinants for cellular growth. The purpose of this study was to assess the influence of the adrenergic hormones on pre-adipocyte growth in primary cell culture. Stromal-vascular cells were obtained from the inguinal pad of young rats and grown in culture for two weeks. Cells were exposed to norepinephrine (NE) during the proliferative phase of growth, labelled by [3H]-thymidine incorporation and then placed on a differentiation promoting medium. Adipocytes and stromal cells were separated using a density gradient, and [3H]-thymidine content was determined for both cell types. NE reduced [3H]-thymidine uptake indicating a reduction in pre-adipocyte proliferation. NE-induced inhibition of pre-adipocyte growth was blocked by the presence of propranolol, whereas phenoxybenzamine had no effect, thereby suggesting that NE-inhibition is through beta-adrenoceptors. Pre-adipocytes were treated with NE for varying lengths of time to investigate whether cells were desensitized to chronic beta-adrenergic stimulation. In addition, adenosine deaminase (ADA) was also applied to eliminate adenosine which may accumulate during NE stimulation. Neither the duration of NE exposure nor ADA treatment affected adrenergic control of adipocyte growth. These studies indicate that NE reduces pre-adipocyte proliferation and therefore may be an important negative regulatory component of adipocyte growth.

Adenosine Deaminase↗
PubMed1990

Evaluation of a simple method for the measurement of cytidine deaminase in serum and comparison with a reference method.

This study was designed to evaluate a cytidine deaminase (CD) assay modified to allow results to be achieved within one working day. Inter-batch variation for samples of mean (SD) CD activity, 10.2 (1.0) units, 17.5 (1.2) units and 31.7 (1.7) units were, 9.8%, 6.9% and 5.4% respectively (n = 26). The reference range (3.2-13.2 U) was similar in males and females and was independent of age. There was close correlation with a reference method (r = 0.96). The mean difference between methods was 2.7 U and the limits of agreement were -1.7 to 7.1 U. The results indicate that the short assay technique can produce results that are sufficiently accurate and precise to be clinically useful.

Arthritis, Rheumatoid↗
PubMed1990

An update of the enzymology and regulation of sphingomyelin metabolism.

Sphingomyelin is found in plasma membranes and related organelles (such as endocytic vesicles and lysosomes) of all tissues, as well as in lipoproteins. Abnormalities in sphingomyelin metabolism have been associated with atherosclerosis, cancer and genetically transmitted diseases; however, except for Niemann-Pick disease, little is known about the mechanism for these disorders. Sphingomyelin biosynthesis de novo involves ceramide formation from serine and two mol of fatty acyl-CoA followed by addition of the phosphocholine headgroup. The headgroup appears to come from phosphatidylcholine, but other sources have not been ruled out. Factors that influence the rate of sphingomyelin synthesis include the availability of serine and palmitic acid, plus the relative activities of key enzymes of this pathway. Sphingomyelin turnover involves removal of the headgroup and amide-linked fatty acid by sphingomyelinases and ceramidases, respectively, which have been found in both lysosomes (with acidic pH optima) and plasma membranes (with neutral to alkaline pH optima). The enzymes of sphingomyelin turnover release ceramide and free sphingosine from endogenous substrates, which may have implications for the participation of a sphingomyelin/sphingosine cycle as another 'lipid second messenger' system.

Animals↗
PubMed1990

The source and significance of raised serum enzymes in rheumatoid arthritis.

Hepatobiliary dysfunction in rheumatoid arthritis has been suggested on the basis of raised serum activity of alkaline phosphatase, 5-nucleotidase, lactic dehydrogenase and gamma-glutamyl transferase, but a specific pathological lesion has not been demonstrated and serum transaminases and bilirubin are almost invariably normal. This paper reports a series of studies designed to determine the tissues of origin of the enzymes and offers an alternative interpretation of the enzymological findings. The results suggest that only alkaline phosphatase originates from the liver, while lactic dehydrogenase and 5-nucleotidase originate from synovial fluid polymorphs and synovial lining cells, respectively. Serum alkaline phosphatase may be induced by inflammatory mediators such as interleukin-1 because it correlates with the acute phase response. Serum lactic dehydrogenase is an integrated measure of polymorph lysis in all joints and offers a marker of joint inflammation more specific than measures such as the ESR. Levels of serum 5-nucleotidase provide information about the activity of the synovium. Finally, because hepatic necrosis does not normally occur, the transaminases may be used to monitor drug toxicity.

5'-Nucleotidase↗
PubMed1988

Serum cytidine deaminase levels after withdrawal of non-steroidal anti-inflammatory treatment in rheumatoid arthritis.

Increases in joint inflammation in nine patients with rheumatoid arthritis were provoked by withdrawal of their non-steroidal anti-inflammatory drugs. Pain score, duration of morning stiffness, Ritchie articular index score, and the number of analgesic tablets consumed reached peaks after five, three, five, and five days respectively compared with values during six days of normal treatment. Changes in serum cytidine deaminase (believed to reflect polymorph turnover in inflamed joints) showed a different pattern, with a sharp peak after two days and a subsequent trough. Possible mechanisms for these differences are discussed.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1988

Sera from pigs infected with Sarcocystis suicanis and cachectin decrease preadipocyte differentiation in primary cell culture.

The macrophage-secreted hormone cachectin depressed lipoprotein lipase activity and lipogenic enzymes in adipose cells. Cachectin reduced differentiation of preadipocytes in cultures of stromal-vascular cells from rat adipose tissue. Differentiation was measured by two methods of estimating lipid accumulation. Adipocytes were separated from the stromal-vascular cells by centrifugation and staining (oil red 0) for intracellular lipid. Lipolytic activity was measured by using esterase histochemistry. Sera from pigs that were infected with Sarcocystis suicanis showed cachectin-like activity compared with sera collected from the same animals before infection. Cachectin and sera collected from infected animals specifically decreased fat cell number without decreasing the stromal-vascular cell number.

Adipose Tissue↗
PubMed1987

Influence of manure gases on puberty in gilts.

To determine whether manure gases can influence onset of puberty in gilts, 42 crossbred gilts were reared from 10 to 40 wk of age on concrete slats over a 1.22-m deep pit that was drained and refilled with clean water biweekly (clean group). Forty-one gilts were reared over a similar type pit where manure was allowed to accumulate (control group). Treatments were in two separate rooms of the same building with similar feeding, water, floor space, lighting and room temperature. Ventilation fans with timer controls in each room were set so fans in the clean environment ran twice as long as fans in the control environment. Aerial concentrations of ammonia in the control room were fourfold higher than in the clean room (21 vs 5 ppm), while aerial concentrations of hydrogen sulfide were similar. Average daily gain and feed efficiency were similar for both groups [.69 vs .72 kg/d (P = .31) and 1.61 vs 1.54 kg feed/kg gain (P = .52)]. From 20 to 40 wk of age, all gilts were exposed to a mature boar three times weekly, utilizing four boars in rotation. Blood samples were collected weekly from each gilt by venipuncture and analyzed for progesterone to establish time of first ovulation. A greater proportion of gilts in the clean group attained puberty by 24 to 26 wk (P less than .05) and 27 to 29 wk of age (P less than .10) compared with the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗
PubMed1986

Legal and regulatory aspects of genetically engineered animals.

The commercialization of genetically engineered food animals will pose a number of legal and regulatory questions. These may be grouped into questions of process and questions of products. The process of animal genetic engineering with artificially constructed vectors will probably be regulated in much the same manner as other veterinary procedures. There may be some discussion, however, as to whether animal drug or animal biologic regulations are more applicable. The products of animal genetic engineering, i.e., transgenic food animals and food products made from them, also raise important questions about product safety and identity. These include whether and how genetically engineered food animals will be subject to federal inspection for wholesomeness, whether artificial vectors, foreign genes, or gene products will adulterate recipient animal tissues, and how food products made from such animals will be labeled. Prior federal experience with the inspection of interspecific hybrids of cattle and buffalo provides a useful basis for further policy developments in the inspection and labeling of genetically engineered food animals. In particular, the inspection of cattle/buffalo hybrids has established a phenotypic (based on appearance) criterion for deciding how novel food animals should be inspected. As the genetic engineering of food animals on a production basis draws nearer, it may be necessary to supplement the phenotypic criterion with genetic (based on pedigree) criteria to assure that the essential characteristics of animals slaughtered under current food statutes are maintained.

Animal Husbandry↗
PubMed1986

Cytidine deaminase activity as a measure of acute inflammation in rheumatoid arthritis.

Cytidine deaminase (CD), a cytoplasmic enzyme, is thought to leak out of damaged cells and can be measured in fluids by a simple biochemical assay. This study has shown that serum CD activity is raised in rheumatoid arthritis (RA) compared with osteoarthritis (OA). Synovial fluid (SF) CD activity was always less than the corresponding serum activity (mean SF/serum ratio = 0.6) in OA but up to 22 times greater than the corresponding serum activity in RA (mean SF/serum ratio = 13.1), suggesting CD production in inflammatory joints. Evidence to support the SF neutrophil as a cell of CD origin is provided by the CD gradient running from cells to SF to synovium. The close correlation between SF CD activity and neutrophil count (r = 0.93) indicates that SF CD activity is an accurate measure of acute synovial inflammation. Weak correlation of serum CD activity with erythrocyte sedimentation rate (ESR) (r = 0.44) and C-reactive protein (CRP) (r = 0.49) implies that CD estimations supply different though related information about rheumatoid disease activity. We suggest that CD released from damaged neutrophils diffuses from all inflamed joints into the blood, so that serum CD activity may provide an integrated measure of joint inflammation more specific than traditional measures such as the ESR.

Arthritis, Rheumatoid↗
PubMed1986

Physical properties of five grain dust types.

Physical properties of grain dust derived from five grain types (soybean, rice, corn, wheat, and sorghum) were measured and reported. The grain dusts were obtained from dust collection systems of terminal grain handling facilities and were assumed to be representative of grain dust generated during the handling process. The physical properties reported were as follows: particle size distributions and surface area measurements using a Coulter Counter Model TAII; percent dust fractions less than 100 micron of whole dust; bulk density; particle density; and ash content.

Dust↗
PubMed1983

The estimation of serum guanosine deaminase activity in liver disease.

An assay for the estimation of guanosine deaminase is described. The method employs guanosine as substrate and after incubation of serum and substrate at 22 degrees C for 18 h the ammonia liberated is estimated using the Berthelot reaction. Absorbance is measured as 625 nm and the catalytic activity read from a standard curve obtained using ammonia standards. The method provides reproducible measurements of serum guanosine deaminase. The results obtained using 'normal' sera have been used to calculate the 'normal range' for the enzyme in serum. Preliminary results suggest that guanosine deaminase is increased in hepatitis and in patients with liver metastases but normal in all other liver diseases including cirrhosis and obstructive jaundice.

Aminohydrolases↗
PubMed1982

Serum deoxycytidylate deaminase as an index of high-risk pregnancy.

Serum deoxycytidylate deaminase (EC 3.5.4.12, dCMP deaminase) activity was routinely estimated over 7 years in 2460 pregnancies. The results confirm that elevated dCMP deaminase activity (greater than 4.8 units) is associated with the development of pre-eclampsia but not with essential hypertension in pregnancy; a high rising level can precede eclampsia. Elevated enzyme activity was also found in women who developed jaundice in pregnancy and in some with apparently normal pregnancies. An unexpected finding was that these so called 'false positive' high levels were associated with all the unexplained intrauterine fetal deaths that occurred later in pregnancy. Although elevated dCMP deaminase levels may be associated with a normal outcome, persisting high levels indicate the need for careful monitoring of fetal well being and, in the presence of any other sign of placental insufficiency, delivery should be expedited.

Clinical Enzyme Tests↗
PubMed1982

Activity of serum cytidine deaminase during pregnancy.

A simple and reliable method for the estimation of cytidine deaminase (cytidine aminohydrolase; EC 3.5.4.5) activity in pregnancy serum is described. This enzyme does not require magnesium for activation and is also more stable than deoxycytidylate deaminase (dCMP deaminase, dCMP aminohydrolase; EC 3.5.4.12). There was excellent correlation between the two enzymes (r = 0.92). Both enzymes showed increased activity in abnormal pregnancy. Both enzymes activities were found to be similar in 1305 maternal serum samples and therefore due to the simplicity of cytidine deaminase estimation it is recommended for the screening of large numbers of antenatal sera for abnormal pregnancies.

Cytidine Deaminase↗
PubMed1980

Biophysical cytochemical investigations of intracellular heparin in neoplastic mast cells.

The thermodynamic binding parameters for intracellular heparin-acridine orange (AO) complexes were determined for Furth murine mastocytoma cells and were found to agree with 1) results from binding studies on heparin-AO complexes in solution, and 2) with biochemical analyses of the cells. The cells exhibited cooperative binding with a binding constant of 1.18 x 10(6) M-1. The cooperative binding constant of heparin-AO in 1 mM buffer was found to be 1.13 x 10(6) M-1. The addition of 1 mM NaCl to heparin-AO system in vitro detectably decreased the cooperative binding constant. Low ionic strength is the only condition in solution under which the cell and solution binding constants are equal. The cells have an average of 1.2 x 10(-14) mol of AO binding sites per cell. Using the biochemically measured heparin content per cell and the amount of AO bound by heparin in solution, 8 x 10(15) mol of sites/cell can be attributed to heparin. The remaining cellular binding sites (4 x 10(-15) mol of sites per cell) are essentially all accounted for by AO binding to DNA, the amount of which is calculated from its previously determined thermodynamic binding parameters. A theoretical isotherm, calculated from the binding parameters of both heparin-AO in solution and DNA-AO complexes in situ, agreed closely with the isotherm experimentally determined for the Furth mastocytoma cells. Ligand-binding analysis yields a binding constant, which may aid in identification of cellular bipolymers, and the number of ligand binding sites per cell. The latter is a measure of the amount of a given intracellular biopolymer present.

Acridine Orange↗